New tablet, new kiosk user, set this user to default to new dashboard, but it always loads the default overview

Bought a Fire HD8 on sale on Prime Day. Installed Fully Kiosk. Set up the new user Full_Kiosk in HA, although it shows the username as full_kiosk (lower case). All this was set up by me, harryfine who is an admin.

Created the new dashboard, called it kiosk, it is blank at the moment. it is not set as admin only. On the same network, I logged in on the tablet as full_kiosk, under settings → dashboards → kiosk I selected the kiosk dashboard and set it to default on that device. Under the user at the bottom of the sidebar, Full_Kiosk (note the capitals in the dashboard field I changed it from overview to kiosk.

I logged out from that same screen on the tablet, logged back in as full_kiosk, and it comes as as the overview dashboard, it is no longer set as the default dashboard, and it no longer is set under my user preferences.

Sure seems like a bug to me. Does anyone have any experience doing this?